Tuning the bandgap in Co-doped Mg(OH)2 nanoparticles

Cobalt (Co) doped magnesium hydroxide Mg(OH)(2) nanoparticles are synthesized by a surfactant-free co-participation method. Scanning electron microscopy (SEM) images show nanometer size Mg(OH)(2) particles in spherically shaped particle-like morphology. Synthesis of these Mg(OH)(2) nanocrystals involves the formation of monomeric MgOH+ ions as the precursor for the Mg(OH)(2) nuclei which finally evolves in spherical particle-like morphology. X-ray diffraction (XRD) confirms the hexagonal crystal structure of the samples. With increasing Co concentration, the absorption spectra of the samples show narrowing of the bandgap from 5.47 eV (for pure Mg(OH2)) to 5.26 eV (for 10% Co-doped Mg(OH2)) effect is attributed to changes in the interaction potentials between Co and the host Mg(OH)(2) lattice due to dopant-induced lattice distortion and the presence of a mixed valance Co2+/Co3+ state.